JPH04263584A - Recorder - Google Patents

Abstract

PURPOSE:To record without generating the doubling of pictures when a still picture is changed at reproduction time. CONSTITUTION:A MUSE signal from a BS tuner 2 is digitalized to be supplied to RAM6A and 6B. The RAM 6A and 6B are alternately written by taking four fields of the MUSE signal as one unit of still picture data. Dummy data DD is inserted between still picture data of each screen to be read out alternately from the RAM 6A and 6B to be supplied to a DAT 50 so as to record. The time for inserting the dummy data DD is time (1/15 seconds) corresponding to the four fields of data in a video system rate. At reproduction time, the role of the two RAMs is changed when the writing of the still picture data in the RAM is completed and the reading from the other RAM goes to the end of one screen of the still picture data. The role of the RAM is not changed during the reading of one screen of the still picture data so that the doubling of two still pictures can be eliminated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus for recording, for example, a MUSE signal as still image data.

0002

[Prior Art] As a method for compressing the transmission signal band of television signals, MUSE (Multiple Sub-
nyquist Sampling Encoding
) is known. In the MUSE encoder, band compression is performed by line offset subsampling in the motion system, and by field offset and frame offset subsampling in the stationary system. On the other hand, in the MUSE decoder, in the motion system, an image is reproduced using only the signal of the current field by interpolation, and in the stationary system, the image is reproduced using the signals of the current field and the previous three fields by interframe and interfield interpolation.

[0003] In the MUSE system, high-definition television signals are transmitted. According to the high-definition standard, the number of scanning lines per frame is 1125, the interlace ratio is 2:1, the aspect ratio is 16:9, the field frequency is 60 Hz, and the line frequency is 33,750 Hz.

FIG. 5 shows the format of a television signal (hereinafter referred to as "MUSE signal") transmitted using the MUSE method. The MUSE signal has 480 samples of data on each of 1125 horizontal lines, with a frame pulse added to the beginning of each frame and a horizontal synchronization signal added to the beginning of each line.

[0005]

By the way, it is conceivable to record such a MUSE signal as still image data, for example, on a DAT (digital audio tape recorder).

As described above, in a still system, images are reproduced using signals of four fields, so when recording MUSE signals as still image data, it is desirable to record in units of four fields.

[0007] Although not mentioned above, the MUSE signal is 16.2MH
If sampled in z and there are 4 fields (2 frames), then 1125 x 2 x 480 = 1,080,000 samples. If one sample is 8 bits, 8,640,
000 bits (≒8.24 Mbits).

[0008] If this one screen worth of still image data is recorded on a DAT, the data recording speed on the DAT is 1
, 536,000 bits (48kHz x 2 channels x 1
6 bits), it will take 5.625 seconds. That is, in the video system, 4×1/60≈66.7 msec worth of data becomes 5.625 seconds worth of data in the DAT system.

Still image data recorded in this way is DA
When played from T, it takes 5.625 seconds to
Still image data for one screen is played back and written to the first memory, then still image data for the next screen is played back and written to the second memory.
1 from the first memory while being written to the first memory.
The average still image data for a screen is 84.3 (5.625 seconds/
66.7 msec) times, and this is the MUSE
The still image is supplied to a monitor television via a decoder and displayed.

[0010] Here, if the intervals between the still image data of each screen recorded on the DAT are narrow, at the same time as the playback of one screen's worth of still image data ends, the next screen's worth of still image data is played back. is started, so the first
The writing and reading states of the second memory must also be switched.

In this case, the DAT system on the input side of the memory and the video system on the output side are asynchronous, and the video system
While reading the still image data for the screen, the first and second
The write and read states of the memory are switched,
At that moment, the two still images become double, resulting in an extremely unsightly screen.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a recording apparatus capable of recording without causing image duplication due to switching of still images during playback.

[0013]

[Means for Solving the Problems] The present invention provides still image data for each screen in a recording device that sequentially supplies and records still image data for a plurality of screens to a recorder whose rate is lower than that of a video system. In between, dummy data corresponding to at least one screen at a video rate is inserted and recorded.

[0014]

[Operation] When recording still image data for multiple screens on a recorder with a lower rate than that of a video system, the still image data for one screen is played back by the playback device and written to the second memory. During this time, still image data for one screen is repeatedly read out from the first memory multiple times and supplied to the video system, and the still image is displayed.

[0015] In this case, if the playback system and the video system are asynchronous, when the playback of one screen's worth of still image data is finished, the video system will be in the middle of reading out one screen's worth of still image data. . Note that the maximum phase shift is a time equivalent to at least one screen at a video system rate.

Therefore, if the roles of the first and second memories are switched at the same time as the reproduction of still image data for one screen is completed, the two still images will be doubled at that moment.

In the above configuration, since dummy data for a time corresponding to at least one screen at the video rate is inserted and recorded between the still image data of each screen, the still image data for one screen cannot be played back. There is no need to switch the roles of the first and second memories at the same time when the video system finishes reading out one screen worth of still image data. can be eliminated.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. This example is an example in which the MUSE signal is recorded as still image data using DAT.

FIG. 1 shows the configuration of the recording system. In the figure, a satellite broadcast signal captured by a satellite broadcast (BS) antenna 1 is supplied to a BS tuner 2. B.S.
The MUSE signal output from the tuner 2 is band-limited by a low-pass filter 3, further converted into a digital signal by an A/D converter 4, and then transferred to sides a and b of a changeover switch 5.
It is supplied to RAMs 6A and 6B as buffers via the side.

The output signal of the A/D converter 4 is supplied to a synchronization detection circuit 7, and the frame pulse signal and horizontal synchronization signal detected by this synchronization detection circuit 7 are supplied to a controller 8. The controller 8 has a frequency of 48kHz x 4 = 192kHz from the DAT50 in order to synchronize with the DAT50.
A system clock CLK is supplied.

Writing and reading to and from the RAMs 6A and 6B are controlled by the controller 8.
6B, when one is in the write state, the other is in the read state. In other words, M in RAM6A or 6B.
When data for 4 fields of the USE signal is written as still image data, RAM 6B or 6A is written respectively.
to DAT50 data recording speed (1,536,000
Four fields of data are read out in synchronization with the data rate (bits/second). In this case, data for 4 fields (8, 6
40,000 bits) is read out with a time of td (5.625 seconds).

Here, while data for four fields is read from one RAM at a recording speed of DAT50, many field signals are supplied as write signals to the other RAM, and the data contents are sequentially updated. Four fields of data are always stored.

After the reading of four fields of data from one RAM is completed, the writing and reading states of the RAMs 6A and 6B are switched. At this time, data for four fields immediately before switching is stored in the other RAM.

Still image data read from the RAMs 6A and 6B is supplied to the a side of the changeover switch 10 via the a side and b side of the changeover switch 9, respectively. Switching of the changeover switches 5 and 9 is controlled by a controller 8. The selector switch 5 is set to a when the RAM 6A is in the write state.
When connected to the side and RAM6B is in the write state b
connected to the side. The changeover switch 9 is connected to the a side when the RAM 6A is in the read state, and is connected to the b side when the RAM 6B is in the read state.

Reference numeral 33 denotes a dummy data generation circuit, and the output signal of this generation circuit 33 is supplied to the b-side fixed terminal of the changeover switch 10. The operation of this generating circuit 33 and the switching of the changeover switch 10 are controlled by the controller 8.

That is, immediately before four fields' worth of data is supplied to the a side of the selector switch 10, the generation circuit 33 generates a time tv (1/15 second) corresponding to four fields' worth of data at the video system rate. dummy data DD is output. As the dummy data DD, for example, 128 level continuous data, 0 level and 255 level alternating continuous data, etc. are selected. Although not mentioned above, RAM6A, 6B
The reading of four fields worth of data from the dummy data DD will be started after the output of this dummy data DD. Also,
The changeover switch 10 is connected to the a side when data for four fields is supplied to the a side, and is connected to the b side when dummy data DD is supplied to the b side.

Therefore, the changeover switch 10 outputs data with dummy data DD added for the time tv to the beginning of each of the four fields of data (as shown in FIG. 3A), and this is supplied to the DAT 50 and recorded. .

Next, FIG. 2 shows the configuration of the reproduction system. In the figure, four fields of data (still image data) sequentially reproduced from the DAT 50 are transferred to the RAM 22 as a buffer via the a side and b side of the changeover switch 21.
A and 22B are alternately supplied and written.

The reproduction signal of the DAT 50 is transmitted to the synchronization detection circuit 23.
supplied to This synchronization detection circuit 23 detects the end of the dummy data DD added to the beginning of four fields of data, and the detection signal SD is sent to the controller 24.
is supplied as a signal (cueing signal) indicating the start timing of four fields of data. Further, the controller 24 is supplied with a 192 kHz system clock CLK from the DAT 50.

Writing and reading of the RAMs 22A and 22B are controlled by the controller 24 based on the detection signal SD and the system clock CLK. Changeover switch 2
1 is controlled by the controller 24, and R
When the AM 22A is in the write state, it is connected to the a side, and when the RAM 22B is in the write state, it is connected to the b side.

When one of the RAMs 22A and 22B is in a write state, the other is in a read state. In other words, when data for four fields of the MUSE signal is written to RAM 22A or 22B, each RAM
Four fields of data are repeatedly read from 22B or 22A in synchronization with a 16.2 MHz clock. In this case, after 4 fields of data have been written to one RAM, the roles of RAMs 22A and 22B are switched when reading from the other RAM reaches the end of the 4 fields of data. be done.

That is, the reproduced signal from the DAT 50 is
When the state is as shown in FIG. 3A, the writing and reading states of the RAMs 22A and 22B are as shown in FIG. 3B and C. For example, when still image data b is written in RAM 22B, still image data t is written in RAM 22A.
It is read out repeatedly at a cycle of v. After the writing end time T1 of the still image data b to the RAM 22B, the RAM 22A
At time T2 when the reading from the still image data a reaches the end, the roles of the RAMs 22A and 22B are switched.

[0033] Then, the still image data b is repeatedly read out from the RAM 22B at the cycle of tv. Also, R
Still image data c is written into AM22A from time point T3 when the dummy data DD of the reproduced signal ends. In this case, the time difference between time T1 and T2 is always smaller than tv, and the reproduced signal at time T2 is always dummy data DD.
becomes.

Four fields of data (still image data) according to the format of the MUSE signal repeatedly output from the RAMs 22A and 22B are transferred to the selector switch 25 a.
The signal is supplied to the MUSE decoder 28 via the side and b side. Switching of the changeover switch 25 is controlled by the controller 24, and when the RAM 22A is in the read state, it is connected to the a side, and when the RAM 22B is in the read state, it is connected to the b side.

The video signals (for example, R, G, B signals) output from the MUSE decoder 28 are supplied to a monitor television 29, and a still image is displayed on the monitor television 29.

In this example, still image data (
Dummy data DD is inserted and recorded for the tv time between 4 fields of data), and during playback, one R
After the still image data has been written to the AM, the roles of the RAMs 22A and 22B are switched when reading from the other RAM reaches the end of one screen's worth of still image data. Therefore, according to this example, the RAM 2
The roles of 2A and 22B are not switched, and it is possible to avoid double still images at the moment of switching.

In the above-mentioned embodiment, dummy data DD is inserted and recorded for the time of tv between the still image data of each screen, but as shown in FIG. Synchronous pattern signal PS at the end of DD
may be arranged. In this case, in the synchronization detection circuit 23 of the reproduction system (shown in FIG. 2), the synchronization pattern signal PS
can be detected and used as a cue signal for the next still image data. In this case, the synchronization pattern signal PS does not necessarily need to be placed at the end of the dummy data DD, but may be placed in the middle or at the beginning. In that case, after detecting the synchronization pattern signal PS, a counter or the like is used to form a cue signal for the next still image data.

Further, in the above embodiment, the time of the dummy data DD is tv, but it may be any time longer than tv. However, as this time becomes longer, the number of still images recorded on the recording medium (magnetic tape) decreases. For example, by inserting dummy data DD for the time of tv, the recording time of still image data for one screen is td(
5.625 seconds) + tv (0.0667 seconds), which is approximately 1
．． This is an increase of 2% (5.6917/5.625-1).

Furthermore, in the above embodiment, data for four fields is used as one unit of still image data, but it is also possible to use two fields or one field as one unit of still image data. Can be applied.

Further, in the above embodiment, the MUSE signal is recorded as still image data on the DAT50, but other television signals, such as N
The present invention can be similarly applied to the case where a TSC television signal is recorded as still image data.

For example, a video signal of frame still images (30 frames per second, 33.3 msec per frame) is processed at 4fsc.
Consider the case where sampling is performed at =14.3 MHz (fsc is the color subcarrier frequency) and recording is performed using DAT50. 1
Still image data for a screen is 14.3MHz x 33.3m
Since seconds x 8 bits = 3,809,520 bits,
Still image data for one screen is approximately 2.4 with DAT50.
Recording and playback takes 8 seconds. In this case, when recording, 33.3 msec of dummy data DD is inserted between the still image data of each screen. Thereby, it is possible to prevent two still images from being doubled during playback, as in the above-described embodiment.

Furthermore, in the above embodiment, DAT5
0 to record still image data,
The present invention can be similarly applied to the case of recording with other recorders whose rates are lower than those of video systems.

[0043]

According to the present invention, dummy data is inserted and recorded between the still image data of each screen for a time corresponding to at least one screen at the video rate, so that one screen can be saved from the RAM during playback. It is no longer necessary to switch between RAM write and read states while reading still image data for 1 screen, and the switch can be made once reading of still image data for 1 screen is completed, preventing duplication of 2 still images. It can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a recording system according to an embodiment.

FIG. 2 is a block diagram showing the configuration of a reproduction system according to the embodiment.

FIG. 3 is a diagram for explaining data processing during recording and reproduction.

FIG. 4 is a diagram showing the structure of an example of dummy data.

FIG. 5 is a diagram showing the format of a MUSE signal.

[Explanation of symbols]

2 BS tuner 6A, 6B, 22A, 22B RAM 7, 23 Synchronization detection circuit 8, 24 Controller 28 MUSE decoder 29 Monitor TV 33 Dummy data generation circuit 50 DAT

Claims (2)

[Claims] Claim 1: In a recording device that sequentially supplies and records still image data for multiple screens to a recorder whose rate is lower than that of the video system, the video system's still image data is recorded between the still image data of each screen. A recording device that inserts and records dummy data for a time equivalent to at least one screen at a rate. 2. The recording apparatus according to claim 1, wherein a synchronization signal for cueing the next screen of still image data is arranged at a predetermined position of the dummy data.